In particular, the bicycle gear to which reference is made in the context of this patent description is the rear one, which moves the chain between the different sprockets of the sprocket assembly associated with the rear wheel of the bicycle.
A rear gear typically comprises an articulated quadrilateral actuation kinematic mechanism that is actuated mechanically by a sheathed cable (mechanically-actuated rear gear) or electrically by an electric motor (electrically-actuated rear gear).
In particular, the rear gear typically comprises a first body fixed to the bicycle frame, a second body that supports a rocker and a pair of articulation connecting-rods that connect the first body and the second body.
The rocker comprises, as its essential elements, an inner plate, an outer plate, a pair of pins integral with the inner and outer plates and a pair of toothed wheels arranged between the inner and outer plates.
Each toothed wheel is rotatably mounted on a respective pin of the pair of pins.
In the prior art, pins are used that consist of screws provided with a head and threaded shank. The pins are mounted at respective pairs of holes made on the outer plate and on the inner plate.
Typically, the threaded shanks of the screws are screwed into threaded through holes of the inner plate, until the heads of the screws abut on the outer plate.
The inner plate is typically made from light alloy such as aluminum or carbon fiber or technopolymer, so as to conveniently make the threading of the relative threaded through holes. In the case in which the inner plate is made of carbon fiber or technopolymer the threaded through holes are made in appropriate metallic inserts.
The Applicant has found that a rocker of the type described above has some drawbacks.
In particular, the Applicant has found that the upper wheel (i.e. the one that is higher up when the rocker is mounted on the bicycle) of such a rocker, in the operative configuration in which the rear gear has selected the largest sprocket of the sprocket assembly (i.e. the sprocket of the sprocket assembly that is closest to the bicycle wheel), is at an extremely short distance with respect to the bicycle wheel, such a distance being called in jargon “X factor”.
The Applicant has observed that, particularly in the case of lenticular wheels, in the case of bumps or irregular road surface the inner plate could accidentally move towards the wheel and interfere and rub against it.
Such a risk is also due to the fact that the inner plate, in order to be able to make a sufficient number of grip threads there, must have a predetermined thickness (which the Applicant has measured to be, for example, equal to about 2.2 mm).
Moreover, given that an end portion of the shank of the screws typically projects with respect to the inner plate, there is the risk of such an end portion being able to rub on the bicycle wheel.
The technical problem at the basis of the present invention is to provide a rocker for a bicycle gear that is constructively simple, cost-effective and reliable and that overcomes the aforementioned drawbacks.